To implement a fully automated process for making high-precision products is becoming the focal point for any future machinery. It is because that in the foreseeable future, the crave for ultra precision dies or parts in industries, such as personal portable 3C products, optoelectronic communication and bio-medication, will be growing unstoppably. However, when it come to machine a ultra-precision product, the complexity as well as the design of the ultra-precision product is restricted by the precision of its machining process, that is, the capability of the machinery implementing the machining process. Therefore, until now, it is still a costly effort to integrate a variety of machining processes in an integration mechanism just for manufacturing a high-precision product.
Wire electrical discharge machining (WEDM) is one of the most accurate non-conventional manufacturing processes available for creating complex or simple shapes or geometries within parts and assemblies. WEDM works by eroding material in the path of electrical discharges that form an arc between a wire electrode and a work piece. WEDM manufacturing is a very desirable manufacturing process when it comes to cutting some of the hardest material used in the industries in high accuracy.
With the growing demand for ultra-precision dies and parts, the market for WEDM machines is expanding as well. However, when the WEDM machines are mass produced, it is difficult to ensure each mass-produced WEDM machine to perform a manufacturing process at the same accuracy, that is, the mass production of WEDM machine will suffer a stability problem. Such stability problem is originated from the complex production process including a plurality of procedures, such as frame casting, parts manufacturing and assembling, and also, from the human error caused by the massive man power used in the complex production process. As WEDM is usually performed in a bath of a working fluid exerting directly on the upper and the lower wire guides at about 20 kg/cm 2 for flushing materials away, the flushing of the working fluid at such high pressure is going to cause the lower wire guide to drop and thus the machining head of the lower wire guide to drift in space since the lower wire guide can be slim and is extending away from its support. It is known that a WEDM machine uses a wire electrode holding between an upper wire guide and a lower wire guide to performs an electrical discharge cutting, and before the cutting is performed, the controller of the WEDM machine will calculated a cutting path for the wire electrode assuming that the wire electrode is a virtue line connecting the machining heads of the upper and the lower wire guides while taking the radius of the wire electrode into consideration for path compensation. Thus, If the machining heads of the upper and lower wire guides are drifting by deformation during a machining process, the wire electrode will not be cutting in the path as expected and thus the machining accuracy is jeopardized.
In the conventional WEDM machines, the structures of those upper and lower wire guides have the following shortcomings:                (1) The wire guides can be deformed by torques originated from the flushing of a working fluid at a high pressure upon such wire guides: As show in FIG. 1, since WEDM is usually performed in a bath of a working fluid exerting directly on the upper and the lower wire guides 10, 12 at about 20 kg/cm2 for flushing materials away and such jet of working fluid is emitted from nozzles on the machining heads of the upper and the lower wire guides 10, 12, each of the machining heads of the upper and the lower wire guides 10, 12 are going to sustain a reaction force of the 20 kg/cm2 flushing working fluid that will cause a torque exerting on the corresponding wire guide and thus eventually cause the wire guide to deform. Especially for the lower wire guide 14, the deformation can be much more severe since its machining head is extending farther away from its support than that of the upper wire guide 10 and its cross section area is smaller.        (2) The deformation of a wire guide is affected by the material and the length of the wire guide as well as by the flushing pressure of working fluid exerting thereon: As the deformation is primarily caused by a torque exerting on a corresponding wire guide, which is equal to the product of the length of the wire guide and the force exerting on the machining head of the wire guide. Thus, different flushing pressures and different lengths will cause different torques, and therefore different deformations. In addition, as the rigidity of the wire guide is dependent primarily upon its material, it is noted that a wire guide made of a material with high rigidity can deform less when compare with those made of materials of less rigidity while subjecting to a same torque.        (3) It is unable to perform an on-line compensation since there is no way of knowing how much a wire guide is deformed: Since current WEDM machines do not provide any means for detecting wire guide deformations so that there is no way to compensation the error of such deformation.        
Therefore, it is in need of a wire electrical discharge machine with deformation compensation ability that can compensate a cutting path error caused by the flushing pressure of working fluid.